Traditional brake systems in a motor vehicle typically include hydraulically actuated wheel brakes, a master cylinder in fluid communication with the wheel brakes, and a brake pedal mechanically connected to the master cylinder via a brake booster. As an operator depresses the brake pedal a booster rod pushes on the booster/master cylinder to move a piston within the master cylinder which pushes hydraulic fluid pressure the wheel brakes, such as calipers or drum brakes, which in turn apply frictional force to rotors or drums, respectively. The activation of the brake booster/master cylinder is resisted or opposed by a force attributable to fluid pressure in the hydraulic fluid channels and the brake pads or linings pressing against the rotors or drums. This resistive or opposing force increases relative to the movement of the brake pedal assembly as additional braking force is applied to the wheel brakes. In other words, the further the brake pedal is pushed the harder it gets to push it. Motor vehicle operators perceive this relationship between movement of the brake pedal assembly and increasing resistive force as “pedal feel” of the brake system. Drivers expect a form of pedal feel from all motor vehicle brake systems.
Motor vehicle brake systems have been designed in which fluid pressure to apply a wheel brake may be created independently of a direct mechanical connection between the brake pedal and the brake booster/master cylinder. Systems such as this are often referred to as a “brake-by-wire” system. Since the direct mechanical connection may be separated during some or all modes, the push back aspect of the pedal feel may not be felt by the operator. Vehicles having a traction battery and regenerative braking capability often require a brake-by-wire system. Since drivers expect a form of pedal feel from all motor vehicle brake, it may be advantageous to provide a simulated pedal feel of a traditional brake system in a brake-by-wire brake system.
As well, in traditional brake systems (non brake-by-wire systems), adjustable pedals have been provided to accommodate drivers of various heights. Thus, the adjustment apparatus allows the pedal/pedal assembly to be moved closer to, or further away from, a driver for improved access. The adjustability of the brake pedal may change the pedal feel, and thus it may be advantageous to provide compensation in a traditional brake system to maintain a substantially consistent pedal feel regardless of adjusted position. In addition, it may be advantageous to provide an adjustable brake pedal for a brake-by-wire system while also providing a substantially consistent pedal feel at all adjusted positions.